1. Field of the Invention
The invention relates to polyamide polymers having hot melt adhesive properties and more particularly relates to polyamide resins prepared by the reaction of an aliphatic diamine with aliphatic dicarboxylic acids.
2. Brief Description of the Prior Art
The prior art is replete with descriptions of polyamide compositions having hot-melt adhesive properties and the methods of their preparation. Representative of the prior art adhesive compositions are those described in U.S. Pat. No. 3,444,026. The latter compositions comprise the reaction product of a dimer fatty acid and a wide variety of diamines including hexamethylene diamine. Copolymerizing dicarboxylic acids including aliphatic dicarboxylic acids such as adipic, sebacic and azelaic acids, are also taught as components of the adhesive compositions.
Polyamide compositions useful as hot-melt adhesives for adhering plastics are also disclosed in U.S. Pat. No. 3,847,875. The latter compositions are the reaction product of 1,8- or 1,9-heptadecane dicarboxylic acid and specific heterocyclic diamines such as piperazine. Copolymerizable dicarboxylic acids such as azelaic, sebacic and adipic acids are also disclosed as components of the adhesives.
In U.S. Pat. No. 3,062,773 disclosure is made of aminopolyamide resins useful as curing agents for epoxy resins. These curing agents include the reaction product of C.sub.19 dicarboxylic acids with large excesses of polyamines (exclusive of hexamethylene diamine). In U.S. Pat. No. 2,891,084, C.sub.19 aliphatic dicarboxylic acids are disclosed and suggestion of their use in preparing polyamide resins by reaction with hexamethylene diamine made. In the latter reference, no disclosure of a useful adhesive polyamide is made.
The hot melt polyamide compositions of the invention are particularly advantageous for their melt viscosity and adhesive strength in adhering poromerics such as leather and metals. The compositions of the invention are particularly useful as an adhesive for shoe manufacture.